[PATCH v6 1/2] fpga: ecp5-spi: add Lattice ECP5 FPGA manager

[Ivan Bornyakov]

Add support to the FPGA manager for programming Lattice ECP5 FPGA over
slave SPI interface with .bit formatted uncompressed bitstream image.

Signed-off-by: Ivan Bornyakov <i.bornyakov@xxxxxxxxxxx>
---
 drivers/fpga/Kconfig    |   7 +
 drivers/fpga/Makefile   |   1 +
 drivers/fpga/ecp5-spi.c | 311 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 319 insertions(+)
 create mode 100644 drivers/fpga/ecp5-spi.c

diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
index 6c416955da53..920277a08ed9 100644
--- a/drivers/fpga/Kconfig
+++ b/drivers/fpga/Kconfig
@@ -263,4 +263,11 @@ config FPGA_MGR_MICROCHIP_SPI
 	  programming over slave SPI interface with .dat formatted
 	  bitstream image.
 
+config FPGA_MGR_ECP5_SPI
+	tristate "Lattice ECP5 SPI FPGA manager"
+	depends on SPI
+	help
+	  FPGA manager driver support for Lattice ECP5 programming over slave
+	  SPI interface with .bit formatted uncompressed bitstream image.
+
 endif # FPGA
diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
index 42ae8b58abce..17c7a3c4b385 100644
--- a/drivers/fpga/Makefile
+++ b/drivers/fpga/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA)	+= zynq-fpga.o
 obj-$(CONFIG_FPGA_MGR_ZYNQMP_FPGA)	+= zynqmp-fpga.o
 obj-$(CONFIG_FPGA_MGR_VERSAL_FPGA)	+= versal-fpga.o
 obj-$(CONFIG_FPGA_MGR_MICROCHIP_SPI)	+= microchip-spi.o
+obj-$(CONFIG_FPGA_MGR_ECP5_SPI)		+= ecp5-spi.o
 obj-$(CONFIG_ALTERA_PR_IP_CORE)		+= altera-pr-ip-core.o
 obj-$(CONFIG_ALTERA_PR_IP_CORE_PLAT)	+= altera-pr-ip-core-plat.o
 
diff --git a/drivers/fpga/ecp5-spi.c b/drivers/fpga/ecp5-spi.c
new file mode 100644
index 000000000000..aa0dd10823a3
--- /dev/null
+++ b/drivers/fpga/ecp5-spi.c
@@ -0,0 +1,311 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Lattice ECP5 FPGA programming over slave SPI interface.
+ */
+
+#include <linux/delay.h>
+#include <linux/fpga/fpga-mgr.h>
+#include <linux/spi/spi.h>
+
+#define	ECP5_SPI_MAX_SPEED_HZ		60000000
+
+#define	ECP5_SPI_ISC_ENABLE		{0xC6, 0x00, 0x00, 0x00}
+#define	ECP5_SPI_ISC_DISABLE		{0x26, 0x00, 0x00, 0x00}
+#define	ECP5_SPI_ISC_ERASE		{0x0E, 0x01, 0x00, 0x00}
+#define	ECP5_SPI_LSC_INIT_ADDR		{0x46, 0x00, 0x00, 0x00}
+#define	ECP5_SPI_LSC_BITSTREAM_BURST	{0x7a, 0x00, 0x00, 0x00}
+#define	ECP5_SPI_LSC_CHECK_BUSY		{0xF0, 0x00, 0x00, 0x00}
+
+#define ECP5_POLL_RETRIES		100000
+
+struct ecp5_priv {
+	struct gpio_desc *program;
+	struct gpio_desc *init;
+	struct gpio_desc *done;
+	struct spi_device *spi;
+};
+
+static enum fpga_mgr_states ecp5_ops_state(struct fpga_manager *mgr)
+{
+	struct ecp5_priv *priv = mgr->priv;
+
+	return gpiod_get_value(priv->done) ? FPGA_MGR_STATE_OPERATING :
+					     FPGA_MGR_STATE_UNKNOWN;
+}
+
+static int ecp5_poll_busy(struct spi_device *spi)
+{
+	const u8 lsc_check_busy[] = ECP5_SPI_LSC_CHECK_BUSY;
+	int ret, retries = ECP5_POLL_RETRIES;
+	struct spi_transfer xfers[2] = { 0 };
+	struct spi_message msg;
+	u8 busy;
+
+	xfers[0].tx_buf = lsc_check_busy;
+	xfers[0].len = sizeof(lsc_check_busy);
+	xfers[1].rx_buf = &busy;
+	xfers[1].len = sizeof(busy);
+
+	while (retries--) {
+		spi_message_init_with_transfers(&msg, xfers, ARRAY_SIZE(xfers));
+		ret = spi_sync_locked(spi, &msg);
+		if (ret)
+			return ret;
+
+		if (!busy)
+			return 0;
+
+		usleep_range(50, 100);
+	}
+
+	return -EBUSY;
+}
+
+static int ecp5_poll_gpio(struct gpio_desc *gpio, bool is_active)
+{
+	int value, retries = ECP5_POLL_RETRIES;
+
+	while (retries--) {
+		value = gpiod_get_value(gpio);
+		if (value < 0)
+			return value;
+
+		if ((!is_active && !value) || (is_active && value))
+			return 0;
+
+		ndelay(10);
+	}
+
+	return -EFAULT;
+}
+
+static int ecp5_ops_write_init(struct fpga_manager *mgr,
+			       struct fpga_image_info *info,
+			       const char *buf, size_t count)
+{
+	const u8 lsc_bitstream_burst[] = ECP5_SPI_LSC_BITSTREAM_BURST;
+	const u8 lsc_init_addr[] = ECP5_SPI_LSC_INIT_ADDR;
+	const u8 isc_enable[] = ECP5_SPI_ISC_ENABLE;
+	const u8 isc_erase[] = ECP5_SPI_ISC_ERASE;
+	struct ecp5_priv *priv = mgr->priv;
+	struct spi_device *spi = priv->spi;
+	struct device *dev = &mgr->dev;
+	struct spi_transfer isc_xfers[] = {
+		{
+			.tx_buf = isc_enable,
+			.len = sizeof(isc_enable),
+			.cs_change = 1,
+		}, {
+			.tx_buf = isc_erase,
+			.len = sizeof(isc_erase),
+		},
+	};
+	struct spi_transfer lsc_xfers[] = {
+		{
+			.tx_buf = lsc_init_addr,
+			.len = sizeof(lsc_init_addr),
+			.cs_change = 1,
+		}, {
+			.tx_buf = lsc_bitstream_burst,
+			.len = sizeof(lsc_bitstream_burst),
+			.cs_change = 1,
+		},
+	};
+	struct spi_message msg;
+	int ret;
+
+	if (info->flags & FPGA_MGR_PARTIAL_RECONFIG) {
+		dev_err(dev, "Partial reconfiguration is not supported\n");
+		return -EOPNOTSUPP;
+	}
+
+	/* Enter init mode */
+	gpiod_set_value(priv->program, 1);
+
+	ret = ecp5_poll_gpio(priv->init, true);
+	if (!ret)
+		ret = ecp5_poll_gpio(priv->done, false);
+
+	if (ret) {
+		dev_err(dev, "Failed to go to initialization mode\n");
+		return ret;
+	}
+
+	/* Enter program mode */
+	gpiod_set_value(priv->program, 0);
+
+	ret = ecp5_poll_gpio(priv->init, false);
+	if (ret) {
+		dev_err(dev, "Failed to go to program mode\n");
+		return ret;
+	}
+
+	/*
+	 * Lock SPI bus for exclusive usage until FPGA programming is done.
+	 * SPI bus will be released in ecp5_ops_write_complete() or on error.
+	 */
+	spi_bus_lock(spi->controller);
+
+	/* Enter ISC mode */
+	spi_message_init_with_transfers(&msg, isc_xfers, ARRAY_SIZE(isc_xfers));
+	ret = spi_sync_locked(spi, &msg);
+	if (!ret)
+		ret = ecp5_poll_busy(spi);
+
+	if (ret) {
+		dev_err(dev, "Failed to go to ISC mode\n");
+		goto out;
+	}
+
+	/* Prepare for bitstream burst write */
+	spi_message_init_with_transfers(&msg, lsc_xfers, ARRAY_SIZE(lsc_xfers));
+	ret = spi_sync_locked(spi, &msg);
+	if (ret)
+		dev_err(dev, "Failed to prepare for bitstream burst write\n");
+
+out:
+	if (ret)
+		spi_bus_unlock(spi->controller);
+
+	return ret;
+}
+
+static int ecp5_ops_write(struct fpga_manager *mgr, const char *buf, size_t count)
+{
+	struct ecp5_priv *priv = mgr->priv;
+	struct spi_device *spi = priv->spi;
+	struct spi_transfer xfer = {
+		.tx_buf = buf,
+		.len = count,
+		.cs_change = 1,
+	};
+	struct spi_message msg;
+	int ret;
+
+	spi_message_init_with_transfers(&msg, &xfer, 1);
+	ret = spi_sync_locked(spi, &msg);
+	if (ret)
+		spi_bus_unlock(spi->controller);
+
+	return ret;
+}
+
+static int ecp5_ops_write_complete(struct fpga_manager *mgr,
+				   struct fpga_image_info *info)
+{
+	const u8 isc_disable[] = ECP5_SPI_ISC_DISABLE;
+	struct ecp5_priv *priv = mgr->priv;
+	struct spi_device *spi = priv->spi;
+	struct spi_transfer xfer = { 0 };
+	struct device *dev = &mgr->dev;
+	struct spi_message msg;
+	int ret;
+
+	/* Toggle CS and wait for bitstream write to finish */
+	spi_message_init_with_transfers(&msg, &xfer, 1);
+	ret = spi_sync_locked(spi, &msg);
+	if (!ret)
+		ret = ecp5_poll_busy(spi);
+
+	if (ret) {
+		dev_err(dev, "Error while waiting bitstream write to finish\n");
+		goto out;
+	}
+
+	/* Exit ISC mode */
+	xfer.tx_buf = isc_disable;
+	xfer.len = sizeof(isc_disable);
+	spi_message_init_with_transfers(&msg, &xfer, 1);
+	ret = spi_sync_locked(spi, &msg);
+	if (!ret)
+		ret = ecp5_poll_gpio(priv->done, true);
+
+	if (ret)
+		dev_err(dev, "Failed to finish ISC\n");
+
+out:
+	spi_bus_unlock(spi->controller);
+
+	return ret;
+}
+
+static const struct fpga_manager_ops ecp5_fpga_ops = {
+	.state = ecp5_ops_state,
+	.write_init = ecp5_ops_write_init,
+	.write = ecp5_ops_write,
+	.write_complete = ecp5_ops_write_complete,
+};
+
+static int ecp5_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct fpga_manager *mgr;
+	struct ecp5_priv *priv;
+	int ret;
+
+	if (spi->max_speed_hz > ECP5_SPI_MAX_SPEED_HZ) {
+		dev_err(dev, "SPI speed %u is too high, maximum speed is %u\n",
+			spi->max_speed_hz, ECP5_SPI_MAX_SPEED_HZ);
+		return -EINVAL;
+	}
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->spi = spi;
+
+	priv->done = devm_gpiod_get(dev, "done", GPIOD_IN);
+	if (IS_ERR(priv->done)) {
+		ret = PTR_ERR(priv->done);
+		dev_err(dev, "Failed to get DONE GPIO: %d\n", ret);
+		return ret;
+	}
+
+	priv->init = devm_gpiod_get(dev, "init", GPIOD_IN);
+	if (IS_ERR(priv->init)) {
+		ret = PTR_ERR(priv->init);
+		dev_err(dev, "Failed to get INIT GPIO: %d\n", ret);
+		return ret;
+	}
+
+	priv->program = devm_gpiod_get(dev, "program", GPIOD_OUT_LOW);
+	if (IS_ERR(priv->program)) {
+		ret = PTR_ERR(priv->program);
+		dev_err(dev, "Failed to get PROGRAM GPIO: %d\n", ret);
+		return ret;
+	}
+
+	mgr = devm_fpga_mgr_register(dev, "Lattice ECP5 SPI FPGA Manager",
+				     &ecp5_fpga_ops, priv);
+
+	return PTR_ERR_OR_ZERO(mgr);
+}
+
+static const struct spi_device_id ecp5_spi_ids[] = {
+	{ .name = "ecp5-fpga-mgr" },
+	{},
+};
+MODULE_DEVICE_TABLE(spi, ecp5_spi_ids);
+
+#if IS_ENABLED(CONFIG_OF)
+static const struct of_device_id ecp5_of_ids[] = {
+	{ .compatible = "lattice,ecp5-fpga-mgr" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ecp5_of_ids);
+#endif /* IS_ENABLED(CONFIG_OF) */
+
+static struct spi_driver ecp5_driver = {
+	.probe = ecp5_probe,
+	.id_table = ecp5_spi_ids,
+	.driver = {
+		.name = "lattice_ecp5_spi_fpga_mgr",
+		.of_match_table = of_match_ptr(ecp5_of_ids),
+	},
+};
+
+module_spi_driver(ecp5_driver);
+
+MODULE_DESCRIPTION("Lattice ECP5 SPI FPGA Manager");
+MODULE_LICENSE("GPL");
-- 
2.37.1